In a scanning probe microscope, a probe is scanned by being relatively moved with respect to the surface of a sample placed on a stage in the XY-plane, to detect a change in physical quantity (tunneling current, interatomic force, or the like) that acts between the probe and the sample surface during the scanning. Then, the relative position of the probe in a Z direction is feedback-controlled so as to keep the physical quantity constant during the scanning. It is thereby possible to measure the surface shape of the sample based on a feedback amount (e.g., see Patent Document 1 below).
FIG. 8 is a schematic diagram for describing a conventional mode at the time of relatively moving the probe on the surface of the sample. FIGS. 9A and 9B are diagrams showing the relationship between the time and the relative position of the probe when the probe is relatively moved in the mode of FIG. 8. FIG. 9A shows a relative position of the probe in an X direction and FIG. 9B shows a relative position of the probe in a Y direction.
As shown in FIG. 8, at the time of relatively moving the probe on the surface of the sample, the following operations are alternately repeated: the operation of relatively moving the probe in the X direction (forward path) and the opposite direction (backward path) to the X direction to reciprocate the probe on one line; and the operation of relatively moving the probe by one pixel at a time in the Y direction to shift the probe. The physical quantity on each line during the reciprocation is thereby detected, and the feedback amount is adjusted using the physical quantity detected on each of the forward and backward paths.
As shown in FIG. 9A, the relative speed of the probe in the X direction is constant both on the forward and backward paths. That is, the probe, which starts being relatively moved in the X direction from a starting position P1, is relatively moved on the forward path at a fixed speed immediately after the start, and the relative movement direction is switched to the opposite direction at a return position P2. At this time, the probe is relatively moved on the backward path at a fixed speed immediately after switching of the relative movement direction, and the probe is returned to the starting position P1. In this manner, the relative movement direction of the probe, relatively moved at a fixed speed, is alternately switched to relatively reciprocate the probe on each line.
As shown in FIG. 9B, the probe is moved in the Y direction by one pixel every time the probe, reciprocated in the X direction and the opposite to the X direction, is returned to the starting position P1. The probe, which starts being relatively moved from the starting position P1 in the Y direction, is relatively moved at a fixed speed immediately after the start, and is stopped when relatively moved just by one pixel.